[leetcode]385. Mini Parser

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本文介绍了一道LeetCode上的编程题目——迷你解析器的解决方案。任务要求从字符串中解析出嵌套的整数列表，并提供了一个NestedInteger类来表示这种结构。文章通过示例详细说明了输入字符串的格式及解析后的结构。

题目链接：https://leetcode.com/problems/mini-parser/#/description

Given a nested list of integers represented as a string, implement a parser to deserialize it.

Each element is either an integer, or a list -- whose elements may also be integers or other lists.

Note: You may assume that the string is well-formed:

String is non-empty.
String does not contain white spaces.
String contains only digits 0-9, [, - ,, ].

Example 1:

Given s = "324",

You should return a NestedInteger object which contains a single integer 324.

Example 2:

Given s = "[123,[456,[789]]]",

Return a NestedInteger object containing a nested list with 2 elements:

1. An integer containing value 123.
2. A nested list containing two elements:
    i.  An integer containing value 456.
    ii. A nested list with one element:
         a. An integer containing value 789.

class NestedInteger {
public:
    // Constructor initializes an empty nested list.
    NestedInteger();

    // Constructor initializes a single integer.
    NestedInteger(int value);

    // Return true if this NestedInteger holds a single integer, rather than a nested list.
    bool isInteger() const;

    // Return the single integer that this NestedInteger holds, if it holds a single integer
    // The result is undefined if this NestedInteger holds a nested list
    int getInteger() const;

    // Set this NestedInteger to hold a single integer.
    void setInteger(int value);

    // Set this NestedInteger to hold a nested list and adds a nested integer to it.
    void add(const NestedInteger &ni);

    // Return the nested list that this NestedInteger holds, if it holds a nested list
    // The result is undefined if this NestedInteger holds a single integer
    const vector<NestedInteger> &getList() const;
};

class Solution {
public:
    NestedInteger deserialize(string s) {
        istringstream in(s);
        return deserialize(in);
    }
private:
    NestedInteger deserialize(istringstream &in)
    {
        int number;
        if(in >> number)
            return NestedInteger(number);
        in.clear();
        in.get();
        NestedInteger list;
        while(in.peek()!=']')
        {
            list.add(deserialize(in));
            if(in.peek()==',')
                in.get();
        }
        in.get();
        return list;
    }
};